Tubing expansion tool

ABSTRACT

The invention relates to a tubing expansion tool and to a method of expanding tubing. In one embodiment, a tubing expansion tool ( 10 ) is disclosed which comprises a body ( 14 ) and at least one expansion member ( 16 ) radially movably mounted on the body ( 14 ) for movement towards an extended configuration describing an expansion diameter for expanding tubing ( 12 ) to a predetermined diameter, the expansion member ( 16 ) being lockable in the extended configuration. In further embodiments, the expansion member ( 16 ) is biased radially inwardly; the expansion member ( 16 ) is moveable in response to both an applied mechanical force and an applied fluid pressure force; and the expansion member ( 16 ) is pivotably mounted with respect to the body ( 14 ).

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a tubing expansion tool. Inparticular, but not exclusively, the present invention relates to atubing expansion tool including an expansion member which is radiallymoveable.

[0003] 2. Description of the Related Art

[0004] A number of different tools have been proposed for carrying outexpansion of downhole tubing such as expandable bore-lining tubing. Theapplicant's International Patent Publication No. WO 00/37766 discloses arotary expansion tool including a number of rollers mounted on radiallymoveable pistons. Fluid pressure urges the pistons radially outwardly,to bring the rollers into contact with tubing to be expanded. The toolis then rotated and advanced axially through the tubing to expand thetubing to a greater internal diameter.

[0005] The rollers are compliant such that if the tool encounters aportion of tubing which cannot be expanded, the rollers can moveinwardly to advance through the restriction.

[0006] However, although offering numerous advantages, use of a toolwith compliant rollers introduces the possibility of the occurrence ofirregularities in the internal diameter of the expanded tubing, whichmay not be appropriate. For example, if it is desired to hang anexpandable liner from borehole casing, a portion of the upper end of theliner may be expanded into contact with the casing to provide hangingsupport for the liner, with another portion of the liner being expandedinto contact with the casing to provide a fluid seal between the linerand the casing. Thus, the liner must be expanded to a determined outerdiameter; if a compliant tool has been utilised, it cannot be determinedthat the liner has been expanded to the appropriate diameter.

SUMMARY OF THE INVENTION

[0007] It is amongst the objects of embodiments of the present inventionto provide tubing expansion tools which allow a predictable degree ofdiametric expansion of tubing in a downhole environment, which can beeasily recovered from tubing during an expansion procedure, and whichoffer improved flexibility in their methods of activation.

[0008] According to a first aspect of the present invention, there isprovided a tubing expansion tool comprising:

[0009] a body; and

[0010] at least one expansion member radially movably mounted on thebody for movement towards an extended configuration describing anexpansion diameter for expanding tubing to a predetermined diameter, theexpansion member being lockable in the extended configuration. It isfurther object of the present invention to utilize a piezoelectricsubstrate to mount the optical transceiver elements of the planarlightguide circuit correctly in the best transmitting and receivingpositions.

[0011] According to a second aspect of the present invention, there isprovided a method of expanding tubing, the method comprising the stepsof:

[0012] providing a tubing expansion tool comprising a body and at leastone expansion member movably mounted on the body;

[0013] moving the expansion member radially outwardly to an extendedconfiguration describing an expansion diameter;

[0014] locking the expansion member in the extended configuration; and

[0015] moving the expansion tool through tubing to be expanded. Thefeedback control device determines whether the optical transmitter andthe optical receiver are disposed at respective optimum positionsaccording to the optical signals received by the optical receiving andtransmitting device and the optical receiver, respectively.

[0016] Providing a tubing expansion tool with an expansion member whichis lockable in an extended configuration allows the internal diameter ofthe tubing after expansion to be accurately predicted. The expansionmember is preferably released from the extended configuration afterremoval of the tool from the tubing. This allows verification that theexpansion member has been correctly locked during the expansionprocedure, and thus that expansion to the predetermined diameter hasbeen performed. Alternatively, the expansion member may be releasablylockable in the extended configuration, and may therefore be unlockedwhilst located in the tubing. This allows retraction of the expansionmember prior to retrieval of the tool to surface.

[0017] Preferably, the tool further comprises a locking assembly forlocking the expansion member in the extended configuration.

[0018] Preferably also, the tool further comprises an activating memberfor moving the expansion member towards the extended configuration. Theactivating member may be moveable between a deactivating position and anactivating position, in the activating position the activating membermaintaining the expansion member in the extended configuration.

[0019] Preferably, the activating member is lockable in the activatingposition, to lock the expansion member in the extended configuration.The activating member may be adapted to be locked in the activatingposition by the locking assembly.

[0020] The locking assembly may include a locking member adapted toengage the activating member when the activating member is in theactivating position, to restrain the activating member and thus maintainthe expansion member in the extended configuration.

[0021] Alternatively, the locking assembly may include a locking membercoupled to the activating member and adapted to engage the body oranother part of the tool when the activating member is in the activatingposition, to restrain the activating member against movement withrespect to the body.

[0022] In a further alternative, the expansion member may be directlylockable in the extended configuration. The locking assembly maytherefore comprise a locking member adapted to engage the expansionmember when the expansion member is in the extended configuration, orthe expansion member may be coupled to the expansion member and may beadapted to engage the body or another part of the tool. Thus, followingmovement of the expansion member to the extended configuration, theexpansion member may be locked against further movement.

[0023] In further embodiments, the expansion member may be hydraulicallylocked in the extended configuration.

[0024] The locking assembly may comprise a mechanical,electro-mechanical or hydraulic locking assembly, or a combinationthereof. The lock member may be mounted in the tool body, in theactivating member, or in an intermediate member between the tool bodyand the activating member. The locking assembly may comprise a lockmember in the form of a snap or lock ring, a latch, lock pin, lockingdogs or keys and may be mechanically, electro-mechanically and/orhydraulically actuated.

[0025] According to a third aspect of the present invention, there isprovided a tubing expansion tool comprising:

[0026] a body; and

[0027] at least one expansion member radially movably mounted on thebody for movement between a retracted configuration and an extendedconfiguration describing an expansion diameter for expanding tubing, theexpansion member being biased radially inwardly.

[0028] According to a fourth aspect of the present invention, there isprovided a method of expanding tubing, the method comprising the stepsof:

[0029] providing a tubing expansion tool comprising a body and at leastone expansion member movably mounted on the body; and

[0030] moving the expansion member radially outwardly to an extendedconfiguration describing an expansion diameter against a biasing forcewhich biases the expansion member radially inwardly.

[0031] The expansion member is biased towards the retractedconfiguration to facilitate removal of the tool from tubing in the eventthat the tool becomes stuck. For example, to expand tubing from thebottom-up, the tool would be located at the bottom of the tubing andactivated to move the expansion member to the extended configuration.The tool would then be drawn upwardly to diametrically expand thetubing. During bottom-up expansion, the tool may encounter tubingregions which cannot be expanded to the desired diameter. By inwardlybiasing the expansion member, the expansion member may be retracted toallow the tool to be advanced through the problematic region.

[0032] Preferably, the tool further comprises a biasing assembly forbiasing the expansion member radially inwardly.

[0033] The tool may further comprise an activating member for moving theexpansion member towards the extended configuration. The activatingmember may be moveable between a deactivating position and an activatingposition, in the activating position the activating member maintainingthe expansion member in the extended configuration. When the activatingmember is in the deactivating position, this de-supports the expansionmember and allows the expansion member to be retracted from the extendedposition. Preferably, the biasing assembly biases the activating membertowards the deactivating position.

[0034] Alternatively, the biasing assembly may directly bias theexpansion member radially inwardly. Thus when the activating member ismoved to the deactivating position, the expansion member may beretracted from the extended configuration by the biasing assembly.

[0035] The biasing assembly may comprise a mechanically,electro-mechanically, hydraulically or pneumatically actuated biasingmember, or a combination thereof. For example, the biasing assembly mayinclude a biasing member in the form of a spring or a sprung member, asolenoid, a piston or any other suitable member for biasing theexpansion member. It will be apparent to the skilled person that anysuitable alternative biasing member may be employed.

[0036] According to a fifth aspect of the present invention, there isprovided a tubing expansion tool comprising:

[0037] a body;

[0038] at least one expansion member radially movably mounted on thebody for movement towards an extended configuration describing anexpansion diameter for expanding tubing, the expansion member beingmoveable in response to both:

[0039] an applied mechanical force; and

[0040] an applied fluid pressure force.

[0041] According to a sixth aspect of the present invention, there isprovided a method of expanding tubing, the method comprising the stepsof:

[0042] providing a tubing expansion tool comprising a body and at leastone expansion member radially movably mounted on the body for movementtowards an extended configuration describing an expansion diameter;

[0043] moving the expansion member to the extended configuration inresponse to a selected one or both of an applied mechanical force and anapplied fluid pressure force; and

[0044] moving the expansion tool through the tubing to diametricallyexpand the tubing.

[0045] This provides a tubing expansion tool which may be activatedeither by application of a mechanical force, by application of a fluidpressure force or by a combination of the two.

[0046] The expansion member may be moveable by an activating assemblyincluding an activating member for moving the expansion member towardsthe extended configuration. The activating member may be moveablebetween a deactivating position and an activating position, in theactivating position, the activating member maintaining the expansionmember in the extended configuration. The activating member may bemoveable in response to an applied mechanical force or an applied fluidpressure force, or the assembly may include an activating membermoveable in response to either an applied mechanical force, an appliedfluid pressure force, or a combination of the two. In a furtheralternative, the activating assembly may include a first activatingmember moveable in response to an applied mechanical force and a secondactivating member moveable in response to a fluid pressure force. Thefirst and second activating members may be associated with separateexpansion members; thus there may be at least one expansion membermoveable to the extended configuration in response to an appliedmechanical force, and at least one separate expansion member moveable inresponse to an applied fluid pressure force.

[0047] The mechanical force may be generated by applying weight to theactivating member or by otherwise moving the member relative to thebody. The fluid pressure force may be generated by circulating fluidthrough the tool or by supplying hydraulic fluid to the tool, forexample via control line. The activating member may comprise a mandrel,a sleeve, pin, rod or other suitable member, or a piston or other fluidactivated member. It will be apparent to persons skilled in the art thatany suitable alternative activating member may be employed.

[0048] Preferably, the expansion member is pivotable relative to thebody. The expansion member may be pivotably mounted on the body. Theexpansion member may therefore be pivotable about the body to moveradially towards the extended configuration. Pivotably mounting theexpansion member relative to the body allows relatively high expansionratios of the tubing to be generated, as relatively large radialmovement of the expansion member is achievable.

[0049] The expansion member may be coupled to an arm or housingpivotably mounted relative to the body, and may comprise a roller, ballor any other suitable member mounted for rotation with respect to thearm. In particular, the expansion member may comprise a generallytruncated cone or conical member, rotatably mounted on a spigot definedby the arm.

[0050] The expansion member may be mounted for rotation about an axisdisposed substantially parallel to a main axis of the body. The rolleraxis may be inclined to the main axis of the body. Alternatively, theroller may be rotatable about an axis disposed substantiallyperpendicular to a main axis of the body. Preferably, the tool comprisesa plurality of expansion members.

[0051] The activating member and/or the expansion member may include acam surface for urging the expansion member to the expandedconfiguration. The cam surface may be inclined such that as theactivating member is moved to the activating position, the activatingmember abuts the expansion member and moves the expansion memberradially outwardly to the extended configuration. When the activatingmember is returned to the deactivating position, the expansion member isde-supported, allowing retraction of the expansion member.

[0052] Preferably, in use, the expansion member describes an unexpandeddiameter less than an unexpanded inner diameter of the tubing. The bodymay also be of an outer diameter less than the unexpanded inner diameterof the tubing. This allows the tool to be run into and through tubing tobe expanded to a desired location, before the tool is activated toexpand the tubing. Alternatively, in use, the expansion member maydescribe an unexpanded diameter greater than or equal to the unexpandedinner diameter of the tubing, and the body may also be of an outerdiameter greater than said diameter of the tubing.

[0053] The tool is preferably a downhole tool for expanding downholetubing. The expansion member may be rotatable about an expansion memberaxis, and said expansion member axis may be inclined with respect to thebody of the tool. The expansion member axis may be inclined towards aleading end of the tool. It will therefore be understood that theexpansion member may describe a smaller expansion diameter towards theleading end of the tool than towards a trailing end of the tool. Thusthe tool may effectively taper towards the leading end.

[0054] The above methods may further comprise the steps of:

[0055] translating the tool through a restriction defining an internalbore diameter smaller than said expansion member expansion diameter; andthen

[0056] moving the expansion member radially outwardly to said extendedconfiguration.

[0057] This may comprise translating the tool through a restriction inan unlined portion of a borehole. It will be understood that an unlinedportion of a borehole is a portion in which no downhole tubing has beenlocated. Alternatively or additionally, this may comprise translatingthe tool through a restriction in the tubing. The tool may thereforehave a particular utility where a restriction is encountered, such as aportion of the tubing which cannot be fully expanded, or where anon-expandable downhole tool or component is located in the tubing orthe open hole.

[0058] The method may comprise expanding an end of the tubing to agreater diameter than a remainder of the tubing, and may compriseforming a bell-bottom in the tubing. A bell-bottom is a portion of thetubing a larger internal diameter than the internal diameter of aremainder of the tubing, optionally also of a larger external diameterthan an external diameter of a remainder of the tubing. The method mayalso comprise as locating a further tubing in said end of the tubing.The further tubing may be expandable and expanded into contact with saidend of the tubing, the tubing comprising a casing and the further tubinga liner, for example.

[0059] According to a seventh aspect of the present invention, there isprovided a tubing expansion tool comprising:

[0060] a body; and

[0061] at least one expansion member pivotably mounted with respect tothe body for movement towards an extended configuration describing anexpansion diameter for expanding tubing to a predetermined diameter.

BRIEF DESCRIPTION OF THE DRAWINGS

[0062] There follows a description of embodiments of the presentinvention, by way of example only, with reference to the accompanyingdrawings, in which:

[0063]FIG. 1 is a longitudinal sectional view of a tubing expansion toolin accordance with an embodiment of the present invention, shown in adeactivated configuration and located in tubing to be expanded;

[0064]FIG. 2 is a view of the tubing expansion tool of FIG. 1, drawn toa larger scale and shown in an expanded configuration during expansionof the tubing;

[0065]FIG. 3 is a view of the tubing expansion tool of FIG. 1, shown inthe deactivated configuration in alternative tubing to be expanded;

[0066]FIG. 4 is a view of the tubing expansion tool of FIG. 3 in theexpanded configuration, drawn to a larger scale and shown duringexpansion of the tubing;

[0067]FIG. 5 is a longitudinal sectional view of a tubing expansion toolin accordance with an alternative embodiment of the present invention,shown in a deactivated configuration;

[0068]FIG. 6 is a view of the tubing expansion tool of FIG. 5, drawn toa larger scale and shown in an expanded configuration;

[0069]FIG. 7 is a longitudinal sectional view of a tubing expansion toolin accordance with a further alternative embodiment of the presentinvention, shown in a de-activated configuration;

[0070]FIG. 8 is a schematic, bottom view of the tubing expansion tool ofFIG. 7 showing expansion members of the tool in both the de-activatedand the expanded configurations; and

[0071]FIG. 9 is a view of the tubing expansion tool of FIG. 7, drawn toa larger scale and shown in an expanded configuration.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0072] Turning firstly to FIG. 1, there is shown a longitudinalsectional view of a tubing expansion tool in accordance with anembodiment of the present invention, indicated generally by referencenumeral 10. The tool 10 is shown located in liner 12 which is to bediametrically expanded. The expansion tool 10 is shown in FIG. 1 in ade-activated configuration which allows the tool to be run through theunexpanded liner 12 to the desired location.

[0073] The expansion tool 10 comprises a hollow body 14 and fourexpansion members 16, each radially moveably mounted on the body 14, formovement towards an extended configuration describing an expansiondiameter, as shown in FIG. 2. Each expansion member 16 includes an ovalsection expansion roller 18 mounted on a piston 20, which is radiallymoveable in slots 22 in a tapered lower end 24 of the body 14.Alternatively, the roller 18 is mounted in a body or housing pivotablymounted to the tool body 14, for example, by a pivot such as the pivot25 shown in the drawings.

[0074] A hollow activating mandrel 26 is mounted in the body 14 forurging the rollers 18 to the extended configuration of FIG. 2. Themandrel 26 is moveable between a deactivating position shown in FIG. 1and an activating position shown in FIG. 2, in response to either anapplied mechanical force, an applied fluid pressure force or acombination of the two. A lower end 52 of the mandrel 26 is truncatedcone-shaped, and defines a cam surface 54 for urging the rollers 18 tothe extended configuration, as will be described below. The expansiontool 10 also includes a locking assembly 35 comprising a snap ring 27located in a groove 29 in the mandrel 26, for locking the rollers 18 inthe extended configuration of FIG. 2.

[0075] An upper end 28 of the mandrel 26 is coupled to a connecting sub30 which allows a mechanical force to be exerted on the mandrel 26 tomove the mandrel between the deactivating and activating positions. Theconnecting sub 30 is in-turn coupled to a tubing string (not shown) fromwhich the tool 10 is suspended, and the sub 30 is axially moveablerelative to the body 14. The tool 10 also includes a biasing membercomprising a spring 36, which biases the mandrel 26 towards thedeactivating position of FIG. 1. In the deactivating position, themandrel 26 de-supports the rollers 18, allowing the rollers to be movedradially inwardly, towards the retracted position of FIG. 1.

[0076] The biasing spring 36 is located between a shoulder 38 in thebody 14 and a shoulder 40 of the connecting sub 30. As will be describedbelow, when the force on the mandrel 26 is removed or reduced, thespring 36 urges the sub 30 and mandrel 26 towards the deactivatingposition of FIG. 1, to de-support the rollers 18.

[0077] The tool body 14 includes an annular guide ring 42 which guidesthe mandrel 26 and a cylinder 44 is defined by an annular floatingpiston 46 mounted between the mandrel 26 and the body 14. The mandrel 26includes a number of ports 48 extending through the wall of the mandrelwhich allow fluid communication between a central bore 50 of the tool 10and the cylinder 44. Seals (not shown) are provided between the piston46 and a shoulder 37 of the mandrel 26 such that the piston defines anupper piston area 29 and a smaller, lower piston area 31, and furtherseals 58, 60 are provided above and below the cylinder 44.

[0078] The seal 58, 60 ensure that pressure is applied to the upperpiston area 29 and that there is no leakage into the chamber of spring36, or past the piston 46. Also, a flow restriction nozzle 33 isprovided at the lower end of the mandrel 26. As will be described below,both the differential piston area and the nozzle 33 allow movement ofthe mandrel 26 by application of fluid pressure, to urge the rollers 18to the extended configuration. Flow ports 62 in the cone 52 allow flowof cooling fluid to the rollers 18 during expansion of the liner 12.

[0079] A method of operation of the expansion tool 10 will now bedescribed, with reference to FIGS. 1 and 2.

[0080] In a top-down expansion procedure, the tool 10 is run into a wellborehole on coiled tubing and into the liner 12. When the tool 10 hasbeen located at the top of the liner 12, fluid is circulated through thebore 50 of the tool, exiting through the nozzle 33. The nozzle 33restricts fluid flow and increases the back-pressure of fluid in thebore 50, pressurising fluid in the cylinder 44 relative to the fluidacting on the lower piston area 31. The combination of the back-pressureof the fluid in the cylinder 44 and the differential piston area urgesthe piston 46 downwardly, carrying the mandrel 26 downwardly to theactivating position of FIG. 2. During this movement, the cam surface 54of the mandrel cone 52 abuts the roller pistons 20, urging the pistonsradially outwardly in their slots 22, to the extended configuration ofFIG. 2.

[0081] At the same time, the tool 10 is rotated by an appropriatedownhole motor, and the rollers 18 are progressively moved outwardly todescribe an expansion diameter greater than the unexpanded internaldiameter of the tubing 12. When the mandrel 26 has moved fullydownwardly, the snap ring 27 locks out against the guide ring 42, tolock the mandrel 26 against return movement to the deactivating positionof FIG. 1. The mandrel 26 is thus locked in the activating position, andmaintains the rollers 18 in the extended configuration of FIG. 1.

[0082] The rotating expansion tool 10 is then translated axially throughthe tubing 12, and the rollers 18 diametrically expand the liner 12 to agreater internal diameter, as shown in FIG. 2. The expansion tool 10 isrotated and translated through the liner 12 to a desired depth, and theexpansion tool 10 is then returned to surface. By verifying that thesnap ring 27 has locked out to restrain the mandrel 26 in the activatingconfiguration, this indicates to the operator that the rollers 18 werecorrectly located in the extended configuration during the expansionprocedure. Accordingly, this provides an indication that the tubing 12has been expanded to the desired, predetermined internal diameterdescribed by the rollers 18 in the extended configuration. The snap ring27 is then released and the mandrel 26 retracts to the deactivatingposition under the force of the spring 36, thus de-supporting therollers 18. The rollers 18 can then be returned to the retractedconfiguration of FIG. 1.

[0083] Turning now to FIGS. 3 and 4, an alternative method of operationof the tool 10 will be described.

[0084]FIG. 3 shows the tool 10 located in borehole casing 64, in thedeactivated position. The tool 10 has been run into the casing 64 on astring together with expandable bore-lining tubing in the form of anexpandable liner 66. An upper end of the liner 66 is shown in FIG. 3,and is located overlapping the casing 64, with a seal sleeve 68 providedon an outer surface of the liner 66, for sealing between the casing 64and the liner 66.

[0085] When the liner 66 has been located in the desired position, thetool 10 is set down on the upper end of the liner 66 and weight isapplied to the mandrel 26, through the connecting sub 30. This moves themandrel 26 downwardly, forcing the rollers 18 outwardly to the expandedconfiguration, and the snap ring 27 locks the mandrel in the activatingposition and thus the rollers 18 in the extended configuration. The tool10 is then rotated and advanced axially through the liner 66,diametrically expanding the liner into contact with the casing 64 asshown in FIG. 4. The tool 10 is advanced through the liner 66 to adesired depth, and then recovered to surface, as described above. Theliner 66 is thus hung from the casing 64 and sealed relative to thecasing 64 by the seal sleeve 68.

[0086] Turning now to FIG. 5, there is shown a tubing expansion tool inaccordance with an alternative embodiment of the present invention, thetool indicated generally by reference numeral 100. Like components ofthe tool 100 with the tool 10 of FIG. 1 share the same referencenumerals incremented by 100. For ease of reference, only the significantdifferences between the structure of the tool 100 with respect to thetool 10 will be described herein.

[0087] The tool 100 includes three expansion member assemblies 116, eachcomprising expansion arms 70 coupled to the tool body 114 by pivots 125and an expansion ball 72 rotatably mounted to the arm 70 for expandingtubing. The arms 70 are spaced 120° apart and are moveable about thepivots 125 between the de-activated configuration of FIG. 5 and theexpanded configuration of FIG. 6 in the same fashion as the tool 10. Themandrel 126 includes a cylindrical lower end 124 and each arm 70includes an inner surface 156 which is recessed (not shown) to define acam surface which abuts the mandrel lower end 124. As the mandrel 126descends, the mandrel urges the arms 70, and thus the expansion balls72, outwardly to the expanded configuration of FIG. 6.

[0088] Pivotably mounting the arms 70 on the body 114 in this fashionallows a high expansion ratio of the tubing as there is a relativelylarge movement of the expansion balls 72 between the de-activated andexpanded configurations.

[0089] Turning now to FIG. 7, there is shown a tubing expansion tool inaccordance with a further alternative embodiment of the presentinvention, the tool indicated generally by reference numeral 200. Thisview of the tool 200 corresponds to a section along line A-A of FIG. 8.It will be understood that the view of the tool 100 shown in FIG. 5 issectioned in a similar fashion.

[0090] Like components of the tool 200 with the tool 10 of FIG. 1 sharethe same reference numbers incremented by 200. Again, only the maindifferences between the tool 200 and the tool 10 will be describedherein.

[0091] The tool 200 includes three expansion members 216 spaced 120°apart and including expansion arms 270 pivotably mounted to the toolbody 214 by pivots 225. Tapered, truncated expansion cones 274 arerotatably mounted on spindles of the arms 270 for expanding tubing whenthe tool is moved to the expanded configuration of FIG. 9. Again, a highexpansion ratio is achieved by the relatively large movement of theexpansion members 216, as shown best in FIG. 8, the position of thecones 274 in the expanded configuration indicated by the brokenreference line. The tool 200 is otherwise similar to the tool 100 ofFIG. 5 and cam surfaces 76 defined by the arms 270 are illustrated inFIG. 7. These cam surfaces 76 abut the lower end 224 of the tool mandrel226 during downward movement of the mandrel, to urge the expansion arms270 outwardly to the expanded configuration.

[0092] In further embodiments of the present invention, the tools 10,100 or 200 may be activated through a combination of mechanical forceapplied to the respective tool mandrel and through circulation of fluidthrough the tool bore to force the mandrel downwardly.

[0093] In still further embodiments of the present invention, theexpansion tools 10, 100 or 200 may be deployed as part of a stringincluding a rotary expansion tool of the type disclosed in InternationalPatent Publication No. WO00/37766. For example, one of the expansiontools 10, 100 or 200 may be disposed in a string including a rotaryexpansion tool of the type disclosed in WO00/37766. The expansion toolof WO00/37766 may be used to create an initial, partial expansion of thetubing 12 during movement of the string through tubing to be expanded,to hang the tubing, in the form of liner carrying a seal from a largerdiameter casing. The expansion tool 10, 100 or 200 is then fullyactivated as described above, to expand the tubing to a determineddiameter, by passing the tool down through the tubing to a desireddepth. The tool is also passed through the interface between the casingand liner, to ensure the liner and the seal are expanded to the correctpredetermined diameter, thus confirming integrity of the connection. Useof a string including both such expansion tools offers flexibility ofoperation in the downhole environment.

[0094] Various modifications may be made to the foregoing within thescope of the present invention.

[0095] For example, the tool may only include locking means or biasingmeans. The tool may be mechanically activated in any alternative fashionsuitable for moving the mandrel down relative to the body. For example,the tool mandrel may be urged downwardly relative to the tool body byrestraining the body and setting weight down on the mandrel.

[0096] The snap ring may alternatively be disengaged downhole, such thatthe biasing spring returns the sub and mandrel to the de-activatedposition. This de-supports the rollers, which are now no longer able toexert an expansion force on the tubing, allowing the expansion tool tobe returned to surface more easily. The snap ring may be releaseddownhole by a release assembly such as release sleeve moved over thesnap ring to cam the ring into the ring slot, allowing movement of themandrel past the guide ring. Alternatively, the tool may include dogs orpins for moving the snap ring inwardly. In a further alternative, thesnap ring may simply be sheared out.

[0097] The mandrel may define a piston in place of a floating annularpiston mounted on a shoulder of the mandrel, the mandrel shoulder maydefine the piston. Thus, for example, the annular piston 46 of the tool10 may comprise an integral part of or may be coupled to the mandrelshoulder 37.

[0098] The tool may be run on jointed tubing and may be driven fromsurface by a kelly or top drive.

[0099] Where the expansion members 16 of the tool 10 are mounted onpivots 25, movement of the mandrel 26 downwardly may rotate the rollers18 about the pivot 25 such that the rollers 18 describe an expandeddiameter for expanding tubing, in a similar fashion to the tools 100 and200 of FIGS. 5 to 9.

[0100] Where the tools are activated by fluid pressure, the respectivetool mandrel may be urged downwardly either by providing the mandrelwith a restriction nozzle to create a back pressure, or by defining adifferential piston area across the floating annular piston, or by acombination of the two, as described above.

[0101] The expansion member may be inclined with respect to the body ofthe tool and may be inclined towards a leading end of the tool, that is,tapering towards said leading end. Indeed, where, for example, theexpansion members 18 of the tool 10 shown in FIG. 1 are not pivotallymounted to the tool body, it will be understood that the expansionmembers are effectively so inclined.

1. A tubing expansion tool comprising: a body; and at least one expansion member radially movably mounted on the body for movement towards an extended configuration describing an expansion diameter for expanding tubing to a predetermined diameter, the expansion member being lockable in the extended configuration.
 2. A tool as claimed in claim 1, wherein the expansion member is mechanically lockable in the extended configuration.
 3. A tool as claimed in claim 1, wherein the expansion member is hydraulically lockable in the extended configuration.
 4. A tool as claimed in claim 1, wherein the expansion member is electro-mechanically lockable in the extended configuration.
 5. A tool as claimed in claim 1, further comprising a locking assembly for locking the expansion member in the extended configuration.
 6. A tool as claimed in claim 1, further comprising an activating member for moving the expansion member towards the extended configuration.
 7. A tool as claimed in claim 6, wherein the activating member is moveable between a deactivating position and an activating position, in the activating position the activating member maintaining the expansion member in the extended configuration.
 8. A tool as claimed in claim 7, wherein the activating member is lockable in the activating position, to lock the expansion member in the extended configuration.
 9. A tool as claimed in claim 8, further comprising a locking assembly including a locking member adapted to engage the activating member when the activating member is in the activating position, to restrain the activating member.
 10. A tool as claimed in claim 8, further comprising a locking assembly including a locking member coupled to the activating member and adapted to engage the tool body when the activating member is in the activating position, to restrain the activating member.
 11. A tool as claimed in claim 1, wherein the expansion member is directly lockable in the extended configuration.
 12. A tool as claimed in claim 11, further comprising a locking assembly including a locking member adapted to engage the expansion member when the expansion member is in the extended configuration.
 13. A tool as claimed in claim 11, further comprising a locking assembly including a locking member coupled to the expansion member and adapted to engage the tool body.
 14. A tubing expansion tool comprising: a body; and at least one expansion member radially movably mounted on the body for movement between a retracted configuration and an extended configuration describing an expansion diameter for expanding tubing, the expansion member being biased radially inwardly.
 15. A tool as claimed in claim 14, further comprising a biasing assembly for biasing the expansion member radially inwardly.
 16. A tool as claimed in claim 15, wherein the biasing assembly comprises a mechanical biasing member.
 17. A tool as claimed in claim 16, wherein the biasing assembly includes a biasing spring.
 18. A tool as claimed in claim 15, wherein the biasing assembly comprises an electro-mechanical assembly.
 19. A tool as claimed in claim 15, wherein the biasing assembly comprises a hydraulic assembly.
 20. A tool as claimed in claim 14, further comprising an activating member for moving the expansion member towards the extended configuration.
 21. A tool as claimed in claim 20, wherein the activating member is moveable between a deactivating position and an activating position, in the activating position the activating member maintaining the expansion member in the extended configuration.
 22. A tool as claimed in claim 21, wherein the activating member is biased towards the deactivating position.
 23. A tool as claimed in claim 15, wherein the biasing assembly directly biases the expansion member radially inwardly.
 24. A tubing expansion tool comprising: a body; at least one expansion member radially movably mounted on the body for movement towards an extended configuration describing an expansion diameter for expanding tubing, the expansion member being moveable in response to both: an applied mechanical force; and an applied fluid pressure force.
 25. A tool as claimed in claim 24, wherein the expansion member is moveable by an activating assembly including an activating member for moving the expansion member towards the extended configuration.
 26. A tool as claimed in claim 25, wherein the activating member is moveable between a deactivating position and an activating position, in the activating position, the activating member maintaining the expansion member in the extended configuration.
 27. A tool as claimed in claim 25, wherein the activating member is moveable in response to either an applied mechanical force, an applied fluid pressure force, or a combination of the two.
 28. A tool as claimed in claim 25, wherein the activating assembly includes a first activating member moveable in response to an applied mechanical force and a second activating member moveable in response to a fluid pressure force.
 29. A tool as claimed in claim 28, wherein the first and second activating members are associated with separate expansion members.
 30. A tool as claimed in claim 25, wherein the activating member comprises a mandrel.
 31. A tool as claimed in claim 25, wherein the activating member comprises a piston.
 32. A tool as claimed in claim 6, wherein the activating member includes a cam surface for urging the expansion member to the expanded configuration.
 33. A tool as claimed in claim 20, wherein the activating member includes a cam surface for urging the expansion member to the expanded configuration.
 34. A tool as claimed in claim 25, wherein the activating member includes a cam surface for urging the expansion member to the expanded configuration.
 35. A tool as claimed in claim 1, wherein, in use, the expansion member describes an unexpanded diameter less than an unexpanded inner diameter of the tubing.
 36. A tool as claimed in claim 14, wherein, in use, the expansion member describes an unexpanded diameter less than an unexpanded inner diameter of the tubing.
 37. A tool as claimed in claim 24, wherein, in use, the expansion member describes an unexpanded diameter less than an unexpanded inner diameter of the tubing.
 38. A tool as claimed in claim 1, wherein, in use, the expansion member describes an unexpanded diameter greater than the unexpanded inner diameter of the tubing.
 39. A tool as claimed in claim 14, wherein, in use, the expansion member describes an unexpanded diameter greater than the unexpanded inner diameter of the tubing.
 40. A tool as claimed in claim 24, wherein, in use, the expansion member describes an unexpanded diameter greater than the unexpanded inner diameter of the tubing.
 41. A tool as claimed in claim 1, wherein the expansion member is pivotable relative to the body.
 42. A tool as claimed in claim 41, wherein the expansion member is pivotably mounted to the body.
 43. A tool as claimed in claim 42, further comprising an arm pivotably mounted to the body, the expansion member mounted for rotation with respect to the arm.
 44. A tool as claimed in claim 1, wherein the tool is a downhole tool for expanding downhole tubing.
 45. A tool as claimed in claim 14, wherein the tool is a downhole tool for expanding downhole tubing.
 46. A tool as claimed in claim 24, wherein the tool is a downhole tool for expanding downhole tubing.
 47. A tool as claimed in claim 1, wherein the expansion member is rotatable about an expansion member axis, and wherein the expansion member axis is inclined with respect to the body of the tool.
 48. A tool as claimed in claim 14, wherein the expansion member is rotatable about an expansion member axis, and wherein the expansion member axis is inclined with respect to the body of the tool.
 49. A tool as claimed in claim 24, wherein the expansion member is rotatable about an expansion member axis, and wherein the expansion member axis is inclined with respect to the body of the tool.
 50. A tool as claimed in claim 47, wherein the expansion member axis is inclined towards a leading end of the tool.
 51. A tool as claimed in claim 48, wherein the expansion member axis is inclined towards a leading end of the tool.
 52. A tool as claimed in claim 49, wherein the expansion member axis is inclined towards a leading end of the tool.
 53. A tubing expansion tool comprising: a body; and at least one expansion member pivotably mounted with respect to the body for movement towards an extended configuration describing an expansion diameter for expanding tubing to a predetermined diameter.
 54. A method of expanding tubing, the method comprising the steps of: providing a tubing expansion tool comprising a body and at least one expansion member movably mounted on the body; moving the expansion member radially outwardly to an extended configuration describing an expansion diameter; locking the expansion member in the extended configuration; and moving the expansion tool through tubing to be expanded.
 55. A method as claimed in claim 52, wherein the expansion member is released from the extended configuration after removal of the tool from the tubing.
 56. A method as claimed in claim 52, wherein the expansion member is released from the extended configuration whilst the tool is in the tubing.
 57. A method of expanding tubing, the method comprising the steps of: providing a tubing expansion tool comprising a body and at least one expansion member movably mounted on the body; and moving the expansion member radially outwardly to an extended configuration describing an expansion diameter against a biasing force which biases the expansion member radially inwardly.
 58. A method as claimed in claim 57, wherein the biasing force acts directly on the expansion member to urge the expansion member radially inwardly.
 59. A method as claimed in claim 57, wherein the expansion member is moved to the extended configuration by moving an activating member from a deactivating to an activating position, and wherein the biasing force urges the activating member towards the deactivating position.
 60. A method of expanding tubing, the method comprising the steps of: providing a tubing expansion tool comprising a body and at least one expansion member radially movably mounted on the body for movement towards an extended configuration describing an expansion diameter; moving the expansion member to the extended configuration in response to a selected one or both of an applied mechanical force and an applied fluid pressure force; and moving the expansion tool through the tubing to diametrically expand the tubing.
 61. A method as claimed in claim 60, further comprising applying a mechanical force by applying weight to the tool.
 62. A method as claimed in claim 60, further comprising applying a fluid pressure force by circulating fluid through the tool.
 63. A method as claimed in claim 60, further comprising applying a fluid pressure force by supplying hydraulic fluid to the tool.
 64. A method as claimed in claim 54, further comprising: translating the tool through a restriction defining an internal bore diameter smaller than said expansion member expansion diameter; and then moving the expansion member radially outwardly to said extended configuration.
 65. A method as claimed in claim 57, further comprising: translating the tool through a restriction defining an internal bore diameter smaller than said expansion member expansion diameter; and then moving the expansion member radially outwardly to said extended configuration.
 66. A method as claimed in claim 60, further comprising: translating the tool through a restriction defining an internal bore diameter smaller than said expansion member expansion diameter; and then moving the expansion member radially outwardly to said extended configuration.
 67. A method as claimed in claim 64, comprising translating the tool through a restriction in an unlined portion of a borehole.
 68. A method as claimed in claim 65, comprising translating the tool through a restriction in an unlined portion of a borehole.
 69. A method as claimed in claim 66, comprising translating the tool through a restriction in an unlined portion of a borehole.
 70. A method as claimed in claim 64, comprising translating the tool through a restriction in the tubing.
 71. A method as claimed in claim 65, comprising translating the tool through a restriction in the tubing.
 72. A method as claimed in claim 66, comprising translating the tool through a restriction in the tubing.
 73. A method as claimed in claim 54, comprising expanding an end of the tubing to a greater diameter than a remainder of the tubing.
 74. A method as claimed in claim 73, comprising forming a bell-bottom in the tubing.
 75. A method as claimed in claim 73, further comprising locating a further tubing in said end of the tubing.
 76. A method as claimed in claim 57, comprising expanding an end of the tubing to a greater diameter than a remainder of the tubing.
 77. A method as claimed in claim 76, comprising forming a bell-bottom in the tubing.
 78. A method as claimed in claim 60, comprising expanding an end of the tubing to a greater diameter than a remainder of the tubing.
 79. A method as claimed in claim 78, comprising forming a bell-bottom in the tubing. 